#include<iostream>
#ifndef FUN_IF
#define FUN_IF

struct listnode
{
    int data;
    listnode* next;

    listnode(){
        data = 0;
        next = nullptr;
    }
    listnode(int x){
        data = x;
        next = nullptr;
    }
};

class list{
private:
    listnode* head;
    int length;
public:
    list();
    // ~list();

    void insert(int x);
    void remove(int x);
    int len();
};
#endif